refactor(intg): use collected button value types

src/components/CalculatorContainer.vue

@@ -1,14 +1,16 @@
 <script setup lang="ts">
 import { computed, ref } from "vue"
 
+import type { PossibleButtonValues } from "@/types/buttons"
+
 import Screen from "@/CalculatorContainer/CalculatorScreen.vue"
 import DigitalButton from "@/CalculatorContainer/DigitalButton.vue"
 import EvaluationButton from "@/CalculatorContainer/EvaluationButton.vue"
 import OperationalButton from "@/CalculatorContainer/OperationalButton.vue"
 
 const valueToDisplay = ref("0")
 const isDisplayEmpty = computed(() => valueToDisplay.value === "0")
-function appendToScreen(valueToAppend: number | string) {
+function appendToScreen(valueToAppend: PossibleButtonValues) {
 	if (isDisplayEmpty.value) valueToDisplay.value = String(valueToAppend)
 	else valueToDisplay.value += ` ${valueToAppend}`
 }